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Threats to endangered species quantified:
What are the causes of species extinction?

by National Sierra Club Staff

Reprinted from Oregon Conifer, Mar/Apr 1999 
This page was last updated on January 06, 2009 .

An article by David S. Wilcove in the August 1, 1998, issue of "Bioscience" takes a close look at exactly why species are going extinct. Biologists are nearly unanimous in their belief that humanity is in the process of extirpating a significant portion of the earth's species.

Scientists mostly agree that habitat destruction is the primary lethal agent affecting 85% of the study's species. This is followed by competition with or predation by exotic species, which affects 49%. Roads affect a wide array of species, including 15% of all endangered species. Outdoor recreation harms 33% of plants and 17% of animals on the endangered species list. Off-road vehicle use is implicated in the demise of approximately 13%.

Logging, mining, and grazing have contributed to the demise of 12%, 11% and 22% respectively, of the endangered species analyzed. Livestock grazing is particularly harmful to plants, affecting 33% of endangered plants. Finally, 14% of endangered species are threatened by disruption of fire regimes in the ecosystems in which they live.

(A Cowfree note: The above figures indicate that grazing alone is as harmful as logging and mining combined. This is something that activists should keep in mind in their efforts to bring about reforms in the management of our public lands.)